ssh/agent: parse constraints when adding keys

Change-Id: I264fc3e3e441d6e5ff7c5aa624eee1018cf9e4de
Reviewed-on: https://go-review.googlesource.com/50811
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>

ssh/agent/server_test.go

@@ -8,6 +8,9 @@ import (
 	"crypto"
 	"crypto/rand"
 	"fmt"
+	pseudorand "math/rand"
+	"reflect"
+	"strings"
 	"testing"
 
 	"golang.org/x/crypto/ssh"
@@ -207,3 +210,50 @@ func TestCertTypes(t *testing.T) {
 		}
 	}
 }
+
+func TestParseConstraints(t *testing.T) {
+	// Test LifetimeSecs
+	var msg = constrainLifetimeAgentMsg{pseudorand.Uint32()}
+	lifetimeSecs, _, _, err := parseConstraints(ssh.Marshal(msg))
+	if err != nil {
+		t.Fatalf("parseConstraints: %v", err)
+	}
+	if lifetimeSecs != msg.LifetimeSecs {
+		t.Errorf("got lifetime %v, want %v", lifetimeSecs, msg.LifetimeSecs)
+	}
+
+	// Test ConfirmBeforeUse
+	_, confirmBeforeUse, _, err := parseConstraints([]byte{agentConstrainConfirm})
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+	if !confirmBeforeUse {
+		t.Error("got comfirmBeforeUse == false")
+	}
+
+	// Test ConstraintExtensions
+	var data []byte
+	var expect []ConstraintExtension
+	for i := 0; i < 10; i++ {
+		var ext = ConstraintExtension{
+			ExtensionName:    fmt.Sprintf("name%d", i),
+			ExtensionDetails: []byte(fmt.Sprintf("details: %d", i)),
+		}
+		expect = append(expect, ext)
+		data = append(data, agentConstrainExtension)
+		data = append(data, ssh.Marshal(ext)...)
+	}
+	_, _, extensions, err := parseConstraints(data)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+	if !reflect.DeepEqual(expect, extensions) {
+		t.Errorf("got extension %v, want %v", extensions, expect)
+	}
+
+	// Test Unknown Constraint
+	_, _, _, err = parseConstraints([]byte{128})
+	if err == nil || !strings.Contains(err.Error(), "unknown constraint") {
+		t.Errorf("unexpected error: %v", err)
+	}
+}